This photograph shows the copper block immersed inside the water by a string suspended from a clamp of the retort stand. Complete the blanks in these sentences. Each blank is worth 1 mark and in all the four questions are worth 5 marks.

1. The copper block should not touch the sides or bottom of the _____________
2. Do you observe the probe of the ___________________ immersed inside the water?
3. The probe appears to be ____________ and _____________ inside the water.
4. This effect is because of ____________ of the light by the water and sides of the curved sides of the beaker.